Asymmetrical Digital Subscriber Lines (ADSL) is an ANSI standard identified as TI.413 issued in 1995 which presents the electrical characteristics of the ADSL signal as it should appear at a network interface. Generally, ADSL is a high-speed communication technology that allows one client modem, such as that at a remote terminal (RT), to be connected to only one central office (CO) modem through one twisted pair telephone line forming a loop. Typically, discrete multi-tone (DMT) modulation is the chosen line code technique standard in a typical ADSL system. Upstream communications, such as from RT to CO, and downstream communications, such as CO to RT, are divided from one another using frequency division multiplexing (FDM) or using echo canceling, allowing the frequency band for upstream communications to be shared with downstream communications thereby increasing the overall data rate over the loop.
Disadvantageously, the ADSL standard allows only one pair of modems (CO and RT) to communicate over a loop at the same time. The CO modem may send a downstream signal while simultaneously receiving an upstream signal from the RT, frame by frame. Similarly, the RT modem may receive the downstream communication from the CO modem and simultaneously send upstream communication signals to the CO modem.
Since the standardization of ADSL communications, there have been introduced varied implementations and customized uses of the ADSL technology, such as disclosed in commonly assigned U.S. Pat. No. 5,479,447 entitled “Method and Apparatus for Adaptive, Variable Bandwidth, High-Speed Data Transmission of a Multi-Carrier Signal over Digital Subscriber Lines,” the teachings of this patent included herein by reference.
As homes and offices become more networked, there are typically multiple communication terminals and devices in the residential house or office, and local networks are likely installed to share resources, such as internet access, printers, and so on. Home networks are particularly unique in that cost and wiring issues are key considerations. The IEEE 1394 standard has been recently developed which provides for data speeds up to hundreds Mbps. However, the IEEE 1394 standard also requires special cabling for connection, and is not adapted to operate over the common twisted pair telephone lines wired typically throughout a home, for example. A new consortium of home networking, known as Home Phoneline Networking Alliance (HomePNA), was formed. HomePNA is able to connect PCs and peripherals within a household through a single pair phone line shared not only with the telephone sets, but also with xDSL services provided by modems exchanging information over the conventional twisted pair phone lines. HomePNA runs at the frequency range from 5.5 MHz to 9.5 MHz, while the Plain Old Telephone Service (POTS) operates in the frequency range under 4 KHz, and the xDSL service operates at the frequency range from 275 KHz to 1 MHz. The current available HomePNA technology can provide 1 Mbps Ethernet local networking, and may reach 10 Mbps in the near future.